Well bit guide



l De@ 30, 1941- 'r'. E. MCMAHAN 2,267,833,l

WELL BIT GUIDE Filed Feb. 9, 1940 r ff L I l ci 5 'rPinnacle-Beendet,time

zasnsssr j WELL-Britannia' Thomas IMcMali'an; Fellows,(}alif.Application1February.9;1940;. Serial No. 318,086

inven tion :reiatesitc fwellffdrilli ticularly 'effectiveifguidesforsf-.well-.-dril1ing bits.

Deepgwells'fsuclhlfasso swelles-andi gas. wellsusuallyshaveoffse c.-noneverticalacr-:crooked-.pon Whenafagdrillingfstool.l orcbit:lsffrun' into aA Well;` ont.. thee-lewe V`endst'ofythe.vdrilling;string` it "thecrooked?ori-offset. parts" rea-king.: away for. scarringitcustorn'aryp in: the rotary' methodiofiwelldrilling.toemployia' mudladen;

performing iotlierffunctionsformsa layer or'cake unconsolidatedearthformationse-areencountered special rotar'yfmudis @usedfiwhichpenetrates the formatlonzrto-;provide-rfa1;:betterrseal and "coating-5 yonrthezwelliwalli'andfthxsvprevent'caving ofthe loose 'l formation;Wlien: af drilling-f.A bitv 1 movlngi downwarrlly-.fin'vlarwelliscars:or; carriesaway `the@ Inudr: cake-1- from; theewell?wallftliee foundationi` oft'err breaks; looses and-f caves; in" behind zthe bit-l'- causingrgconsiderabletroubler. The. mudlayeror 25 ,allioftenf'faccumulates: L. on f cake fzf rom :the Vwell the f well'.bitrasthecbit s." run t into f. the '-,welL-L and mudsf-,unorf-'rballs'rfup theffcutting Iparts aso that the vbit cannotoperatefeiectivelwwhen it reaches.l

the; bottom. of the awelllf.

It "is ran: object"v of athis-invention to providea well .bit-guidethatspreventsfthev bit from scar-i ring;disturbing:orf-,scrapingawayathel f mud filter cake=on the. ,wellfwallfwhenzthe bit: is -rlowered into rthefvvell, and that-prevents: mud`Avfrom'th'e well wall 'from ,accumulating'onthe cutting .-parts.

Another -zobject'tofs/this :invention .isf-to :provide the:mudgfiilter:cakef from:` the..;well` wall L in the eventzifit lengagesthe -wa'llas.thebitipasses downthe :W en.

throughfanfol-set,noneverticalor crooked partof Another; objectief`:"thfisn'nvention'z'is Ato provide easily-.f and."quickly;I appliedofthe i bit' when the.

free circulations ofi fluidi-iithrough .the drilling string and bit andth'at does YnotV interfere with.orma-teriallyr-delay;thefdrillingfaaction1of the bitf wheni the-bitreachesffthef-b'ottom" of-:the .welllAnotlernobjecttof-thisf-invention'aisr-to provide' a" bit guidef ofthe'vcl'iaracterH referred. toA that ngtoolsxand-a relatesi f.morefparticularly to fshoeseor `guides:` for is readily broken up,drilled up, dissolved, or reduced to fragments when the bit is put intooperation at the bottom of the well. I

Another object of this invention is to provide l' a friable, frangibleor Adrillable bit guide formed of va material having a low specicgravity or a specic gravity comparable to that of the drilling iiuid, sothat its fragments or cuttings are quickly flushed from the ,well by thecirculation fluid yemployed in the usual drilling operations.

Another object of this invention is to provide a. bit guide of thecharacter referred to that may be easily and inexpensively constructedfor use gnt'spractically all types and forms of well drilling A furtherobject of this invention is to pro- Avide abit guide ofthe characterreferred to that isV` easy to install and that is simple and inexpensiveto manufacture.

The various objects and features of my invention will be fullyunderstood from the following detailed description of typical preferredforms andv applications ofv the invention, throughout Ywhichdescriptionreference is ma'de to the accompanying drawing, in which:

Fig; 1 is a side elevation of a typical drag lbit for'use in the rotarymethod of well drilling equipped with one form of guide of theinvention. Fig. 2 is an enlarged, horizontal detailed sectional viewtaken substantially as indicated by line^-22 on Fig. 1. Fig. 3 is a sideelevation of a roller bit or rock bit for use in the rotary method ofWell drilling provided with another form of guide of the invention. Fig.4 is an enlarged, horizontal, detailed sectional view taken as indicatedby line 4-4iof Fig. 3 and Fig. 5` is an enlarged fragmentary sectionalView illustrating an alternative means for securing a [guide to abit. f

The bit guides of the present invention may be varied -and modifiedgreatly in construction, design and materials to adapt them for useunder different conditions and on bits of various types. .Inv thefollowing detailed disclosure I will describe typical forms andapplications of the invention, it being understood that the invention isnot to be construed as limited.` to the particular forms or applicationsabout t be described, as itvbroadly contemplates the' provision of aguide formed for attachment to a wellbit, shaped to prevent the-bit frombreaking XNaway or disturbing the mud cake on the welltwall when the.

otherwise destroyed when the bit is put into operation.

In Figs. 1 and 2 I have illustrated a rotary well drilling bit of thedrag type equipped with one form of guide of the invention. The bit inFigs. 1 and 2 comprises a body I0 secured to the lower end of a rotarywell drilling string S and blades II projecting downwardly and outwardlyfrom the body I0. In the particular case illustrated there are foursubstantially equally spaced cutting blades II. The blades Il havesharpened or bevelled lower parts tion at the bottom of the well boreand have substantially vertical outer edge I3. Circulation ports I4 areprovided in the lower end of the bit body III to discharge thecirculation fluid or rotary mud.

The bit guide shown in Figs. 1 and 2 may be said to comprise, generallya application to the bit, and means I6' for attaching the body I to thebit.

The guide body I5 is designed for ready attachment to the well bit andis formed to prevent the cutting blades II and other parts of the bitAfrom injuring the mud cake layer on the wall of the well when the bit isrun down through the well. The guide body I5 may be varied greatly inconstruction and conguration without departing from the invention. Inthe typical case lillustrated the guide body I5 isa generally annular ortubular element having a continuous annular side wall. The upper andlower ends of the tubular or annular body I5 are open to permit a freemovement and flow of iiuid through the guide.` As illustrated theinterior of the guide body I5 may be substantially uniform in diameter.The exterior of the guidebody I5 is shaped to assure the downwardmovement of the bit and guide through the well with a minimum of injuryto the well wall. The upper portion of the guide body I5 may begenerally cylindrical while the lower portion or major portion of theguide body is tapered downwardly and inwardly or is provided with asurface I1 downwardly and inwardly.

curved surface II may extend to the lower ex-' tremity oi the or mergewith tapered or rounded surface I1 is preferably, though notnecessarily, smooth and is such that its engagement with the wall of thewell results in a minimum of damage It will be seen that the tapering orcurved surface I'l may wipe or slide along the well wall withoutscarring, breaking loose or disturbing the mud cake.

The upper end of the guide body I5 may be shaped to conform to the lowerportion of the well bit. In the construction illustrated the upper endI8 of the body I5 is iiat and generally horiraontal and is provided withspaced notches I9 for receiving the lower end portions of the bit bladesII. The notches I9 may be shaped to rather accurately conform to theactive lower parts I2 of the blades Il. The guide body I5 isproportioned so that its external surface or at least the externalsurface o! its upper portion is outside of or flush with the outer edgesI3 of the cutting blades I I. This proportioning of the body I5positively prevents contact of the cutting edges I2 with the wall of thewell when the bit ismoved through the well. It 'may be preferred to formor shape the lower part of the guide body I5 in such a manner with itsengagement guide body I5 and may approach I2 for acting on the formathatrounds or curves,

This tapered or, 45

with the bottom o the well prevents turning of the guide. Thus, asillustrated in Fig. 1, the lower end of the body I5 may have serrationsor teeth 25 for engaging the bottom wall of the well to resist turningof the guide body lI5 when the bit is set down and rotated.

In accordance with the invention the guide body I5 is frangible,friable, drillable or soluble to be readily broken up, shattered,drilled up or dissolved when the bit reaches the bottom of the I welland, isput'into operation. Considering the guide body I5 for inventionin-its broadergaspecttheguide body I5 may be constructed of anymaterialthat is brittle, crushable, or iriable so that it breaks up when the bitis set down on the bottom of the well,

vvthat readily cracks, parts or divides into reasonably small parts whenthe bit is set down on the vbottom of the well, that is softer than thema- `terial of the bit to be readily drilled up when the bitis rotatedat the bottom of the well,

or that is soluble in the water or other duid in the well to readilydissolve so that it does not interiere with the bit operation. Thematerial of which the bit body I5 is .formed I nay, of course, have twolor more ofthe characteristics mentioned. Further, it maybe preferred vtoconstruct the body I5 of two'or more materials having the selectedcharacteristics. It is contemplated that the guide body I5 be formed ofwood, phenolic compositions such as Bakelite and-other plastics, ceramicmaterials, cement, drillable, metals such as aluminum, aluminumalloys,copper, copper alloys, pewter, Dow metal or cast iron, rubber,

rubber compositions with or without fabric,vnatu ral or artificialstone, papier mch, pressed iiber, glass.

` or otherwise shaped or fabricated. While I have the internal wall ofthe body. The

to the mud iilter cake. v

shown the guide body I5 constructed in one piece it is to be understoodthat it may be sectional or fabricated from a number of suitably con-`nected sections. v I

The means I5 for securing or attaching the guide body I5 to the bit ispreferably such that theguide may be quickly secured in` itsopera Thesecuring means I6A tive position on the bit. may be variedgreatly-without departing from the invention. In the construction beingdescribed transverse openings 2I. are formed in the bit blades II andopenings 22 are formed in the body I5 to register with the openings 2I-.`Rods or pins 23 arepassed into the openings 22 to extend through theopenings 2l; -The pins 23 engaged in the openings 2| and 22 dependablysecure the guide body I5 to the well bit. When thebody I5 is arranged inits proper position on the lower end of the bit the openings 22 arealigned with the openings 2| to receive the pins 23.V Where thecharacter of the material, of which the body I5 is formed, permits,thebody may be secured to the bit by molding or casting the body on thebit. If the body I5 is formed of or includes rubber or other resilientmaterial, the resiliency of the material may secure the guide to thebit. In other cases the guide may be cemented or adhesively secured tothe 'bit or maybe welded, soldered or brazed to the'bit.

or soluble material capable of being shaped, by casting or working andthat ishwater or oil In the use or operation of the'bit guide ill tratedin Figs. 1 and 2, the body I3 is engaged against the lower end of thebit to have the notches I3 receive the lower parts of the blades Thepins 23 are then passed through the openings 22 to cooperate with theopenings 2|. 'Ihis attaches the guide to the blt and conditions theassembly for running into the well. The blt is run into the well on thelower end of the string S in the usual-manner. During the downwardpassage of the blt through the well the guide body directs or guides thebit and prevents the bit parts from contacting or injuring the lining ormud cake on the well wall. The sloping or curved guide surface |1 mayengage the wall in crooked or 'set parts of the well to guide the bitthrough such well portions. The engagement of the guide surface |1 withthe lining or mud cake on the well wall does not result in detachment,scarring, or scraping of the lining or mud. The guide body I5 projectingdownwardly from the lower end of the bit and'covering or en-l gagingunder the cutting parts positively prevents the cutting jparts fromdigging into or scraping the wellwall.. The bit may be run to the lowerend of the well without digging into or injuring the side wall ofthewell at any point. When the bit has reached the bottom of the well it isset down, that is, the weight, or a portionof the weight of the drillingstring S is applied to the bit. This weight is, of course. transmittedto the bottom of the well through theguide body I5. Where the body I5 isformed of friable. frangible or brittle material of the characterreferred to above, the weight imposed on the guide body may cause thebody to break or crumble.

When the bit has reached the bottom of the well and is in condition tobegin the drilling operation the string S is rotated with a suitablefeed pressure or load applied to the bit. The bit operated in thismanner soon crushes or drills up the guide body I5. If the bit body I5is formed of a drillable material such as a soft metal, rubber, fibrousmaterials, stone, or the like, the cutting parts of the bit rapidlydrill the guide into small fragments or particles. When the body I3 isconstructed of a brittle, friable, or frangible material such as glass,Bakelite, cement or the like the rotating bit soon breaks the guide intosmall fragments. The circulation uid discharged from the ports |4 of thewell bit flushes away the particles of the broken up or drilled up guideand the circulation fluid flowing upwardly in the well carries the guidefragments to the ground surface. 'I'he guide effectively guides the bitthrough the Vwell to its operative position and is then quickly andeasily broken up or drilled up,- leaving the bit exposed for freeoperation. The guide in addition to preventing the bit from injuring thewell wall prevents mud from the well wall from accumulating or gatheringlon the cutting parts of the bit and the bit is clear and ready foroperation when the guide is broken up or drilled up.

The well bit illustrated in Figs. 3 and 4 comprises a bit -body 30securedl to the lower end of the drilling string S and provided withsets of downwardly 1 projecting legs 3|. Outer roller cutters 32 arerotatably supported between outerpairs of legs 3| to cut vthe well boreto gauge and to form the outer portion of the well. A series of crosscutters or inner cutters'33 is rotatably supported between another setor pair of legs 3| and serve to drill away the inner portion of the wellject downwardly beyond the legs 3| and the other body parts to actfreely on the formation at the bottom of the well.

The guide of the invention illustrated in Figs.

3 and 4 may be said to comprise, generally, an guide body 34 and means35 for securing the guide body to the well bit.

The guide body 34 is constructed and shaped to be easily applied to thewell bit and to prevent contact of the rollers 32 or 33 with the wallofthe well. The guide body 34 may be varied in shape and constructiondepending upon the kind of material used. In the case illustrated thebody 34 embodies a minimum of material to be light in weight and cheap,and yet has ample strength. The body 34 includes a pair of alignedhorizontally projecting wings 36 for engaging under the cross or innercutters 33. The wings 3B have concave upper sides to receive the pro-Ijecting lowerportions of the cutters I3 and have convex or conformingunder sides. The outer jacent ends of the inner legs 3|.

bore. The toothed roller cutters 32 and 33 pro- 73 ends of the wings 33project beyond or are ilush.

with the outer ends of the cutters 33 and the ad- Rather heavy or thickparts 31 extend outwardly at opposite sides of the wings 36 and joinsubstantially vertical legs or wings 38. 'I'he upper sides of thevertical wings 33 are concaveor provided with notches 33 located andshaped to receive the lower parts of ',the cutters 32 and the outer legs3| of the bit. The outer surfaces of the-Wings 38 are beyond or at leastflush with the outer ends of the cutters 32 and their legs 3| to preventthese parts from contacting the side wall of the well bore when the bitis run into the well.

The outer surfaces 4D of the wings 38 are preferably convex and.) asbest illustrated in Fig. 3 of the drawing, slope or curve downwardly andinwardly with respect to the longitudinal axis of the bit. These convexcurved surfaces 4U effectively guide the bit through offset or crookedportions of the well while preventing the bit from gouging into orinjuring the well wall. A transverse web or brace 4| may extend betweenand connectv the spaced wings 38 to strengthen the construction. Asshown in Fig. 4 of the drawing the bracing web 4| may be quite thin. Theweb 4| operates under compression to brace or support a wing 38 when thewing strikes or engages against the side wall of the well bore. Thesupporting or bracing web 4| may or may not extend downwardly to thelower ends of the Wings 33. Spaced ports 42 may be provided in the parts38 to permit a free discharge of the circulation fluid through theguide. The guide body 34 oonstructed as just described may be anintegral casting l,or may be fabricated from several pieces. A In Figs.3 and 4 of the drawing the means 35 for attaching the guide to the bitincludes flexible elements for binding or tying the guide to the bit.These flexible elements may be rubber bands, rope, cords, straps, orwires. In the case illustrated the flexible securing elementsv are inthe nature of wires 43. The wires 43 have their lower ends fixed to theguidebody 34 .and the upper portions of the wires are adapted to exetend about selected parts of the bit. As shown the wires 43 may passupwardly around the bit to engage over the legs 3| and the end portionsof oppositely extending wires 43 may be twisted together as at 44. Thewires 43 may be cast in the guide body 34 or may be secured to the guideIbody by pins, screws, or the like.

The guide body 34 illustrated in Figs. 3 and 4 broken up, crushed,drilled up or dissolved when the 'bit has reached the bottom of thewell. The guide of Figs. 3 and 4 may be constructed of any suitable orselected friable, frangible, drillable or soluble material. For example,it may be formed of any of the materials mentioned in the description ofthe guide body I5. 'I'he securing means I6 illustrated in Figs. l and 2of the drawing may be utilized to secure the guide body 34 of Figs. 3and 4 to the bit or the wires 43 illustrated in Figs. 3 and 4 may, ifdesired, be employed to secure the guide body i to the bit.

In employing the guide of Figs. 3 and 4 the guide is secured to the bitwhen the bit is to be run into the well. The guide is merely arranged inthe proper position on the lower end of the bit and suitably secured inplace by the wires. The bit is then run into the well on the lower endof the string S. As the bit passes downwardly in the well the guidedirects the bit and may prevent the bit from contacting the side wall ofthe well. The surfaces 40 and other parts of they guide body 34 may wipeagainst or engage the mud cake on the wall of the well without gougingor injuring the same. The guide prevents the roller cutters 32 and 33and the supporting legs 3| from scraping against or digging into thewell wall and is effective in preventing mud from the well wall fromgathering on the cutters and accumulating on the bit. When the bit hasreached the bottom of the well a suitable load or. feed pressure isapplied to it and the string is rotated in the usual manner. Thepressure applied to the bit breaks up or shatters the guide body 3| whenthe body is formed of brittle frangible or friable materials, and thedrilling action of the bit quickly drills up the guide when the guide isformed of wood, drill'able metal, or otheni drillable material. Thefragments of the broken or drilled up guide are flushed from the well bythe rotary mud or circulation fluid discharged from the bit. When theguide has been broken up, crushed, or drilled up the bit is exposed forfreeoperation.

I The body l5 or 34 of the guide, or parts of the saine may beconstructed of characteristically colored material or materials so thatreturns of the broken up or drilled up guide are easily recognized inthe rotary mud or drilling Huid discharging from the well. This providesan accurate means for determining the time required for the circulationto return from the Well bottom to the ground surface.

Fig. 5 of the drawing shows an alternative means for attaching or xing aguide of the invention to a well bit. The construction of Fig. 5includes spaced spring clips 50 whose inner ends are embeddedw in orotherwise fixed to the body 5| of thel guide. As illustrated theembedded inner parts of the fingers 50 may be bent or curved to bebetter. anchored The outer parts of the spring fingers have inturnedlugs 52 for engaging over a surface 53 of a bit part 54. The springngers 50 may automatically engage the bit part 54 to secure or to assistin securing the frangible or drillable guide to the bit. The attachingmeans of Fig. 5 may, if desired, be employed in connection with any formof guide of the invention.

Having described only typical preferred forms and applications of myinvention, I do not Wish to be 1imited`or restricted to the specificdetails herein set fotig, but wish to reserve to myself any variationsbrmodifications that may appear' to those skilledsin the art or fallWithin the scope of the followirigclaims:

Having described my invention. Ivclaixn;

guide comprising-a body shaped tofreceive the lower portions of saidroller, cutters to preventl the cutters vfrom contactingrthe'wall ofthey welly when the tool is run `lntothe well.v and. means for securingthe-,body to the-tool, ythe'body-beingv frangible to bereadilybroken-upA or `drilledup by the tool when thel tool'zis operatedin: the well.

2. A guide for a welldrilling toolhaving cutdownwardly and inwardly` tbguide the tooll through the well.` and means for attaching the.

body to the tool, the body being-formed of drillabie material to bedriued-upby said ycutting i parts when the tool is operated'in the well.

3. Aguidefora rotary well'drilling-bithaving fluid discharge means, the`guide comprising-fa guide body to be arrangedxon the/lower endof the bitand including portions for covering'theactive bit parts to preventthem,fromdigginginto the side wall of the well whenthe bit isbeing rundownthrough the well, saidbody having a.

passage for maintaining said fluid discharge means in communication withthe well, the guide body being formed ofdrillable materialoflafspecificgravity comparable withsthat ofthe drilling the tool and including upperportions recessed 'to receive said roller cutters, and alower portiontapered downwardly and'inwardlyto guide the-Y tool and body downwardlythroughthe well,v and;` means for attaching thea-bodyzto'the tool, the.f body being formed ofy drillable material tov be` readily drilled up bythetool4 when the` tool -on its lower end, the guideincluding'a tubularv"guide body having recesses in its upper end for the exposed parts ofthe roller cutters and designed to prevent the cutters from digging intothe wall of the wellwhenthe bitxis lowered into the well, and means forfacilitating the attachment of the body to the bit.A

'7. A guide for a rotary 'rock bit-.having roller` cutters exposed atits lower end, the guide comprising a guide body to be arranged at thelower end of the bit, the body being formed of drillable material andincluding wings` for'tting under the exposed portionsfof theV cutters,anda web extending between the wings.,

8. A guide for a rotary welldrillingtool having a cutting vpart andfluid discharge means, thel guide comprising a body ,having a `portionkfor agences covering the lower side o! the cutting p'art and shaped toguide the tool through the well without digging into the well wall. thebody having a passage for maintaining said -Iiuid discharge means incommunication with the well bore. and means for securing the body to thetool, said means including a pin received in openings in the tool andguide body.

9. A guide for preventing the cutting parts of a rotary well drillingtool `from injuring the wall o1' the well when the to'ol is loweredthrough the well, the guide con'iprising-a. guide body to be arranged atthe lower vend of the wol and comprising parts for underlying andgenerally conformv ing tothe cutting parts and presenting guide surfacesfor contacting the wall of the well to prevent injurious contact of thetool with the well wall, the body and its said parts lying entirelywithin the circle dened by the outermost portion of the tool when `thetool is rotated, and means for securing the body to the tool.

10. A guide for a well ldrilling tool having an exposed roller cutter atits' lower end, the guide comprising a body o! drillable materialarranged at the lower end oi the tool and having a portion generallyconforming to and protruding below the exposed lower side oi. the rollercutter to prevent the cutter from contacting the wall o! the well whenthe tool is lowered through the well, and means for securing the body tothe tool, the peripheral portion of .the body being shaped to leavegenerally vertical passages for the ow of iluids;

11. A guide for a well bit having. cutting parts A on its lower end anda circulation opening comprising a guide body for arrangement on thelower end of the bit to cover its cuttingparts, the body having arounded lower end for guiding the bit downwardly in the well and havinga port for maintaining said opening in communication with the well,andmeans for securing the body to the bit, the body being formed of areadily drillable material to' be drilled up by the bit.

VTHOMAS E. McMAHAN.

